Method and apparatus for delivering a high pressure gas from a cryogenic storage tank

ABSTRACT

A cryogenic tank assembly has a pump which discharges into an accumulator which is located in the cryogenic storage area. This reduces the space required for the device as well as the functioning of the device. The high pressure fluid in the accumulator remains at a cryogenic temperature. The system may also include a heater to deliver high pressure gas form the liquid storage volume.

FIELD OF THE INVENTION

This invention relates to a gas delivery system.

BACKGROUND OF THE INVENTION

Developments in combustion engine technology have shown that compressionignition engines, known as diesel-cycle engines, may be fueled bygaseous fuels without sacrifices in performance or efficiency. Examplesof such fuels include natural gas, methane, propane, ethane, gaseouscombustible hydrocarbon derivatives such as methanol and hydrogen.Substituting diesel with such gaseous fuels generally results in cost,availability and emissions benefits over diesel. These developments,however, require such gaseous fuels to be delivered to the engine forcombustion at high pressures.

Such prior art high pressure gas delivery systems, however, have beenburdened by challenges arising from the need to provide a practical gasfueling system that supplies adequate on-board fuel storage while, atthe same time, ensuring that the platform integrating the powergeneration system, be it stationary power or vehicular power, is notunduly burdened by additional equipment and/or large fuel tanks. Thepresent invention allows, amongst other things, for a fuel deliverysystem that helps to:

-   minimize the space required for such a system;-   maximize the operating time or range of such gas powered vehicles;    and,-   deliver a gas at the required operational pressures.

Natural gas and other gaseous fuels can be stored in tanks either ascompressed gas (CNG in the case of natural gas), or cryogenically as aliquid (LNG in the case of liquefied natural gas). The present inventionis directed to a method and apparatus that utilizes cryogenic storage.By way of example, the energy density of LNG, depending on itscomparative pressure and temperature, is approximately three times thatof CNG, thereby providing a significant storage advantage over CNGsystems. Natural gas stored as LNG allows for more fuel to be stored perunit volume.

Cryogenic liquids are liquids that boil at temperatures belowapproximately 200K. Such gases include, by way of example, natural gas,nitrogen, methane, hydrogen, helium and oxygen. While, as mentionedabove, there are advantages to utilizing LNG and other liquefied gases,cryogenic storage presents its own challenges.

The goal of a fuel delivery system based on cryogenic fuel, is toprovide a warm pressurized gaseous fuel to a fuel injector from a coldliquefied store of such fuel. Some prior art systems have accomplishedthis by pumping cold liquid fuel from a cryogenic tank utilizing a pumpphysically separate from the tank so as not to burden the cryogenicenvironment with a heat leak source. The pump elevates the pressure ofthe fuel and delivers it to a heater where the fuel is heated to apre-determined temperature suitable for use as a gaseous fuel. Further,where occasions arise in which a pressurized fuel is required to meet asudden demand that cannot be immediately met by the pump alone, anaccumulator may follow the heater thus allowing for a ready supply offuel to be stored at or near the approximate conditions required forinjection as a gaseous fuel into a combustion engine.

One potential goal of utilizing a gaseous fuel is to replace dieselfuel. However, in light of the delivery system described above, agaseous fuel delivery system would require three more physicallyseparate components than is the case for a similar diesel fuel deliverysystem, namely, a physically removed pump, accumulator and heater.Moreover, numerous fittings and connectors are required to join togethersuch a fuel system each of which is a potential failure point or leakpath compromising the reliability of such a system as a whole.

The subject invention significantly reduces:

-   the space required for such a fuel system;-   the material costs associated with building this system;-   the potential failure points within the gas fuel system; and,-   the exposed cryogenic components of the fuel delivery system.

One way of dealing with the space and reliability issues arising with afuel delivery system similar to the one described above is toincorporate a pump or an equivalent pressurizing system into thecryogenic tank. Prior art delivery systems have contemplated such pumps.For example see U.S. Pat. Nos. 4,472,946 and 5,327,730.

A concern with introducing a pump directly into the cryogenic tank isthat it may create a potential heat leak thereby reducing the holdingtime of the liquefied gas, that is, the time prior to which the reliefpressure valve opens to vent gas so as to avoid excessive pressureswithin the tank. Moreover, some prior art fuel delivery systems utilizein-tank centrifugal pumps and vaporizers. Centrifugal pumps, however,work best where relatively low pressure gas must be provided. Indiesel-cycle engines, the high pressure direct injection of gaseousfuels requires pressures far in excess of those that can be practicallyprovided by centrifugal cryogenic in-tank pumping systems. Pumpingsystems utilizing a centrifugal pump are appropriate for transfer pumpsand fueling station operations.

A similar problem arises where heating systems are used to providepressurized gas. Such systems boil gas within the cryogenic tank andrelease it from its liquefied state in this fuel delivery system atbetween 15 and 125 psig (103 to 861 kPa). These systems are alsounsuitable for high pressure direct injection engines where improvedefficiency and emissions can be achieved.

The discussion in this application generally considers a system thatprovides a pressurized gas from a liquefied store of that gas. However,for the purposes of this application, it will be understood that anyreferences to fluids include liquids as well as liquids pressurizedabove the supercritical point of the gas of interest. Similarly, anyreferences to gases include gases as they are generally defined as wellas gases pressurized above the supercritical point of those gases. Moregenerally, if the desired substance to be delivered is to be deliveredat a pressure placing it above the supercritical point of the substance,then that substance generally will also be included in any reference toa gas where corresponding fluid is, at some point in the gas deliverysystem, at a lower temperature and pressure prior to being delivered.

SUMMARY OF THE INVENTION

The present invention is a cryogenic tank assembly that includes avessel with a cryogen space capable of storing a cryogenic fluid at aninitial pressure. The assembly further includes a pump that has anintake opening so that it can receive a quantity of the cryogenic fluid,pressurize it to a pressure above its storage pressure and deliver it toan accumulator within the cryogen space. The accumulator includes astorage volume to hold the pressurized fluid so that it is availabledepending on the demands of the end user.

A further embodiment of the invention includes a housing that surroundsthe accumulator or that part of the accumulator that is within thecryogen space in the event that a portion of the accumulator liesoutside of the cryogen space. The housing extend from and is attached tovessel and helps to support the accumulator and/or the pump within thecryogen space.

A further embodiment of the invention includes a heater that accepts thepressurized fluid from the accumulator and delivers a pressurized gas ata temperature greater than the initial temperature at which the fluid isstored. Some or all of the heater may also be disposed within thecryogen space. Further, some portion or all of the heater may also beplaced in the housing noted above along with that percentage of theaccumulator in the housing. Where a heater is included, the housing maythen be used as a thermal insulator between the accumulator and cryogenspace as well as the heater and the cryogen space, if desired. That is,the housing may provide a thermal insulating space between an inner walland outer wall of the housing. Generally, a thermal insulator may beused to insulate the heater from the cryogen space.

The heater included in the invention may in, in a further embodiment,include a heating substance and at least one channel for housing thatheating substance. The heating substance should be capable of warmingthe cryogenic fluid to convert it from a fluid to a gas as desired. Theincluded heating substance may be a heating fluid capable of beingcirculated through one or more channels found in the heater. Oneembodiment of the invention contemplates delivering a fuel from thedelivery outlet of the heater for use in an engine as well as utilizingthe engine coolant as a heating fluid.

A further embodiment of tank assembly includes a heater with a fluidpassageway for directing the fluid from through the channel noted aboveto a delivery outlet. The fluid passageway may be defined by a pipe.

A further embodiment of the invention includes a cryogenic tank assemblythat has an outer jacket surrounding the vessel that provides for avessel insulation volume between the outer jacket and the vessel. Theinsulation space may be a vacuum space. Further, that insulation spacemay be in communication with the insulation space provided by thehousing noted above. One possible method of providing this embodiment isto have an inner wall attached to the jacket and an outer wall attachedto vessel. Both walls would join at their respective ends in the cryogenspace.

A further embodiment may include one or more pipes through theinsulation space found in the housing allowing for access between thearea outside the jacket and the cryogen space.

A further embodiment of the invention includes one or more reciprocatingpumps for delivering the pressurized fluid.

A further embodiment of the invention includes one or more drive unitscapable of driving the pump. The drive unit may be disposed outside ofthe cryogen space and may be in communication with the pump via a pistonrod running between the drive unit and the pump.

A further embodiment of the invention includes an accumulator thatincludes a sleeve which defines an accumulator space as well as astorage vessel that defines the storage volume. The storage vessel maybe a coil tube. Further the sleeve may also be a thermal insulatorinhibiting thermal conduction into the cryogen space. The accumulatorspace may also include insulators includes thermal convection inhibitorsas well as thermal conduction inhibitor including an evacuated space inthis accumulator space. This is helpful where a heater is incorporatedinto the assembly.

Any material in the insulation space or in the accumulator spacedesigned to reduce heat transfer may be chosen such that it falls below15 W/m×K. In a further embodiment, the cryogenic tank assembly mayinclude a pump, accumulator and heater integrated together wherein theaccumulator would be integrated between the pump and heater. Integratedconnections between each component may help to eliminate any potentialfailure point.

In a further embodiment of the invention, the accumulator may bedisposed within a tank assembly space defined by an outer jacket of thecryogen tank. As such, the space between the outer jacket and the vesselmay be used to house and support the accumulator, or, when used, theheater.

The present invention also contemplates a method of receiving a quantityof a fluid from a cryogen space at an initial pressure, pressurizingthat fluid and storing the fluid within an accumulator disposed withinthe cryogen space wherein the fluid is readily available for deliverywithin a pre-determined pressure range. Further, the method may includeheating and delivering the fluid as a pressurized gas where the fluidfrom the accumulator is heated.

The fluid in question in the invention may be at a pressure above orbelow the supercritical point of that fluid and the gas may too be aboveor below the supercritical point of the delivered gas. The gasdelivered, however, must be at a higher pressure than its pressure instorage prior to pumping and being delivered to the accumulator. Also,where a heater is incorporated, the temperature of the delivered gasmust at a temperature above that of the fluid found in storage prior tobeing pumped and delivered to the accumulator.

The present invention includes embodiments that draw from a stored fluidprior to pumping that includes fluids that comprise at least one ofmethane, methanol, ethane, propane, hydrogen, oxygen, butane, methane,ethane or other hydrocarbon derivatives that are gases at roomtemperature and atmospheric pressure, as well as, generally, a fluidthat comprises an element that is combustible as a gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a cryogenic tank assembly thatincludes an apparatus for delivering a high pressure gas.

FIG. 2 is a cross sectional view of a preferred embodiment of theapparatus.

FIG. 3 is a perspective view of the apparatus.

FIG. 4 is an exploded view of the apparatus.

FIG. 5 is an exploded cross sectional view of the tank assembly.

FIG. 6 is an enlarged partial cross sectional view of a preferredembodiment of the apparatus showing the drive section and the cold endwhen the pump piston is completing a retraction stroke.

FIG. 7 is a cross sectional view of a preferred embodiment of theapparatus showing the drive section and the cold end when the pumppiston is completing an extension stroke.

FIG. 8 is a cross sectional view of the heater section.

FIG. 9 is a cross sectional view of the support and barrier walls withinan embodiment of the cryogenic tank.

FIG. 10 is a cross sectional view of an alternate configuration of thecryogenic tank assembly that includes an apparatus for delivering a highpressure gas.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)

Throughout the following description specific details are set forth inorder to provide a more thorough understanding of the invention.However, the invention may be practiced without these particulars. Inother instances, well known elements have not been shown or described indetail to avoid unnecessarily obscuring the present invention.Accordingly, the specification and drawings are to be regarded in anillustrative, rather than a restrictive, sense.

Generally, the subject invention relates to a fuel delivery system,namely, a cryogenic tank assembly that incorporates a cryogenic tank andan integrated apparatus comprising a pump and accumulator that is foruse in a cryogenic environment. A heater may also be incorporated intothe apparatus downstream of the accumulator.

With reference to FIG. 1, cryogenic tank assembly 10 is shown withapparatus 12 incorporated for the most part within vessel 13. Referringto FIGS. 2 and 3, apparatus 12 incorporates four distinct sections: coldend 14, accumulator 16, heater section 18 and drive section 20. In theembodiment shown, only drive section 20 extends beyond the cryogenicvessel. With reference to the cross sectional side view found in FIGS. 1and 4, generally, a fluid pressurizing means such as a pump is housed inor embodied by cold end 14. Accumulator 16 is defined herein ascomprising accumulator coil 24 and also the components that enableaccumulator coil 24 to function as an accumulator as shown in thesection generally identified as accumulator 16. A heater is housed in orembodied by heater section 18, and a pump driver is housed in orembodied by drive section 20.

Returning to the tank assembly generally, cryogenic tank 10 includesouter jacket 91 and vessel 13. Cryogen space 88, enclosed by vessel 13,allows for a volume of cryogenic fuel to be stored as a fluid. Further,in the embodiment shown, insulation space 17 is included between thevessel and the outer jacket. This space may be evacuated to provide athermal insulator between cryogen space 88 and the outer jacket 91.

FIG. 5 shows an exploded view of tank assembly 10 and apparatus 12illustrating further the cooperation of these components. Extending intothe tank is support wall 90 that houses and supports apparatus 12. Inthe embodiment shown, support channel 21 defined by support wall 90extends into cryogen space 88. A barrier wall 92 is spaced apart fromand surrounds support wall 90 wherein this wall is integrated into tankassembly 10 via a connection with vessel 13. This barrier wall alsoextends into cryogen space 88 and defines further insulation 94 spacebetween support wall 90 and barrier wall 92. Insulation space 94 may bein communication with or sealed from insulation space 17.

When assembled tank assembly 10 finds apparatus 12 fitted throughopening 86 and secured in support channel 21 wherein, in the embodimentshown, the accumulator and heater are generally disposed in cryogenspace 88 supported directly by support member 90 and insulated from thecryogen space by insulation space 94. The pump defined by cold end 14 inthe discussed embodiment, is directly exposed to cryogen space 88.

The embodiment discussed contemplates a natural gas fuel deliverysystem, that is, one where LNG is disposed in cryogen space 88. However,it is not limited to such a system. Generally, the discussion to followcan be adapted to, by way of example, fluid phases of hydrogen, methane,ethane, gaseous combustible hydrocarbon derivatives as well as oxygen asa combustion element.

Referring in more detail to the apparatus component of the tankassembly, by way of example, a preferred style of pump is areciprocating piston pump as shown in the figures. Referring to FIG. 4,the pump comprises compression cylinder 42 within which piston 38 isdisposed, dividing compression cylinder 42 into intake chamber 40 andpressure chamber 46. Intake chamber 40 is further defined by end plate41, which seals one end of compression cylinder 42. The opposite end ofcompression cylinder 42 is sealed by intermediate plate 96, whichfurther defines pressure chamber 46. In a preferred arrangement, tierods 102 are employed to hold compression cylinder 42 between end plate41 and intermediate plate 96.

Fluid may flow into intake chamber 40 from a fluid store in cryogenspace 88 through intake tube 34 and then through inlet check valve 36.Both intake tube and inlet check valve are preferably associated withend plate 41. Piston 38 is dynamically sealed against the interior wallsof compression cylinder 42 as is known to those skilled in the art.Piston 38 is movable within compression cylinder 42 under the influenceof a pump driver housed in driver section 20, which is linked to piston38 by piston shaft 80. Seals between piston shaft 80 and intermediateplate 96 prevent fluid from escaping therebetween.

Piston check valve 44 allows the one-way flow of fluid from intakechamber 40 to pressure chamber 46. Pump discharge check valve 48 isdisposed within a discharge passage leading from pressure chamber 46.Pump discharge check valve 48 allows the one-way flow of fluid frompressure chamber 46 to accumulator coil 24.

In a preferred embodiment, at least a portion of the accumulator storagevolume is defined by accumulator coil 24, which is a tube in the shapeof a coil. Pressurized fluid received from the pump may be stored withinthe accumulator storage volume. As shown in the illustrated embodiments,accumulator coil 24 may be conveniently disposed around piston shaft 80.Accumulator 16 encloses accumulator coil 24 between intermediate plate96 and boundary flange 63. At least one tie rod 104 parallel to pistonshaft 80 may be employed to hold accumulator 16 between intermediateplate 96 and boundary flange 63. An accumulator with a coiled storagevolume, while only one possible embodiment, is advantageous as it adaptswell to temperature and pressure changes within the system. However, anyone of many alternate accumulator designs may be used. These includeaccumulator cylinders or other storage vessels.

In the illustrated embodiment, the LNG or other fluid flows fromaccumulator coil 24 to heater section 18 through fluid outlet 25. Theaccumulator is separated from heater section 18 by boundary flange 63which is preferably made from a material selected to reduce heattransfer from heater section 18 to accumulator 16. For example, boundaryflange 63 may be made from G10 glass fibre composite which has a thermalconductivity of about 2.1 W/m×K.

Similarly, accumulator sleeve 84 extends from intermediate plate 96through to boundary flange 63, housing the accumulator coil 24 anddefining accumulator space 59 within accumulator 16 helping to preventheat transfer from the heater section into accumulator 16 and the pump.Insulating material may be included in the accumulator space such asconvection barriers, conductive thermal insulators, an evacuated space,or a combination of such thermal insulation measures.

It is preferable for the fluid within the accumulator to be maintainedat colder temperatures since warming the pressurized fluid will decreaseits density and may even cause it to be converted to a gas negating thebenefits of storing the fluid in a denser state compared to storing thesame fluid in a gaseous phase. Accordingly, it is desirable to preventheat from being transferred from heater section 18 to accumulator 16 tomaximize the amount of fluid that can be stored in the accumulator.

By way of example, in the case of natural gas, pressurized liquefiednatural gas, depending upon the operational conditions, may be aboutthree times denser than the same quantity of pressurized natural gas ina gaseous form. By maintaining LNG or fluid within accumulator coil 24,each incremental increase in the accumulator coil volume corresponds to,utilizing the example above, an equivalent three fold increase in acorresponding volume of the same fluid where that fluid is a gas. Inother words, by placing accumulator 16 upstream of the heater andthermally isolated therefrom, a greater density can be stored per unitof accumulator volume. Utilizing the same example, an accumulator coilvolume of approximately 0.3 litres of natural gas equals approximately0.90 litres of natural gas found in prior art accumulators designed tostore fuel at pressures similar to that of the gas exiting apparatus 12.

Heater section 18 is described with reference to FIGS. 2 and 8. In apreferred arrangement, a heat exchanger is employed to transfer heat tothe pressurized fluid from a heat exchange fluid housed in the heatexchanger that is capable of warming the pressurized fluid. Thepressurized fluid flows sequentially from fluid outlet 25 through heaterintroduction tube 54, inner tubular coil 56, outer tubular coil 58, andthen finally through delivery nozzle 68. The amount of heat transferredto the pressurized fluid is sufficient to convert the pressurized fluidto a gas.

Introduction tube 54 and inner tubular coil 56 are disposed within innerheat bath channel 60 and outer tubular coil 58 is disposed within outerheat bath channel 64. Inner channel 60 communicates with heat exchangefluid inlet 70 (shown in FIG. 2). Channel passageway 72 allows a heatexchange fluid to flow from inner channel 60 to outer channel 64. Outerchannel 64 communicates with heat exchange fluid outlet 76 (shown inFIG. 2).

Rod sleeve 85 extends from intermediate plate 96 through to drive headflange 82, preventing heat exchange fluid from leaking past the sealsand bearings associated with piston shaft 80. Heater sleeve 19 extendsbetween drive head flange 82 and boundary flange 63, further definingouter channel 64.

A feature of the illustrated preferred apparatus is that the pump,accumulator coil 24 and the heater are integrated in series. This iscontrary to conventional systems which located an accumulator proximateto the end user and downstream from the heater. Another advantage isthat the pump may be coupled directly to accumulator coil 24 which, inturn, may be directly coupled to the heater without the necessity ofinterconnecting piping and the additional joints associated therewith.The method of operating the apparatus is described below. In operation,piston 38 is at rest or being actuated in a retraction stroke or anextension stroke. The events occurring during a retraction stroke aredescribed first.

With reference to FIG. 6, piston 38 has just completed a retractionstroke by moving in the direction of arrow 120 from a position proximateto end plate 41 to a position proximate to intermediate plate 96. Inletcheck valve 36 is opened and fluid has flowed into intake chamber 40through intake tube 34. At the same time, fluid that was in pressurechamber 46 (shown in FIG. 7), has been pressurized to a pressure thatholds piston check valve 44 closed. The retraction of piston 38 has alsocaused the volume of pressure chamber 46 to be reduced whereby earlierin the retraction stroke, the fluid pressure within pressure chamber 46was elevated to a pressure higher than the pressure of the pressurizedfluid within accumulator coil 24, causing pump discharge valve 48 toopen, resulting in some of the pressurized fluid flowing from pressurechamber 46 to accumulator coil 24.

Of course, as would be apparent to a person skilled in the art, it wouldbe possible to feed LNG or another fluid from pressure chamber 46directly into accumulator coil 24 without passing it first through acheck valve, however, operation of the apparatus and gas delivery systemas a whole is enhanced by including pump discharge check valve 48.Amongst other things, the inclusion of pump discharge check valve 48helps to reduce pressure variations downstream of the pump.

The introduction of pressurized fluid into accumulator coil 24 frompressure chamber 46 displaces pressurized fluid already withinaccumulator coil 24 such that pressurized fluid flows throughaccumulator fluid outlet 25 and into heater section 18 (see FIG. 8).

The operation of heater section 18 will be described with reference toFIG. 8. Pressurized fluid enters heater section 18 from accumulatorfluid outlet 25 through heater introduction tube 54. The pressurizedfluid entering heater section 18 may still be at a cryogenic temperaturethat may be lower than the freezing temperature of the heat exchangefluid. To reduce the likelihood of freezing the heat exchange fluid,heater introduction tube 54 directs the pressurized fluid to a locationproximate to where the heat exchange fluid is first introduced into theheater. In the illustrated embodiment, heat exchange fluid is firstintroduced into inner heat bath channel 60 near drive head flange 82.Accordingly, the coldest part of inner coil 56 is exposed to the warmestpart of the heat bath.

The heat exchange fluid flows through inner channel 60 and outer channel64 in the same general direction as the pressurized fluid flowingthrough inner tubular coil 56 and then outer tubular coil 58. Dependingon the operating conditions for the particular application for which theapparatus is employed, and, in particular, the temperature of thepressurized fluid and the temperature of the heat exchange fluid, thelength of the pressurized fluid coil within the heat bath is determinedso that the pressurized fluid exits heater section 18 as a gas that hasbeen heated to a temperature within a pre-determined temperature range.The gas will then also be delivered from the apparatus at a temperaturewithin a pre-determined pressure range.

When the apparatus is employed to deliver a gaseous fuel to an engine,the engine coolant can be used as a suitable and convenient heatexchange fluid that may be delivered to the apparatus. In such anapparatus, engine coolant that has been heated after passing through thecooling jacket of the engine may be delivered to the heat bath in heatersection 18 where it is cooled prior to being returned to the enginecooling system.

A complete pump cycle includes a retraction stroke and an extensionstroke. The extension stroke is described with reference to FIG. 7,which depicts piston 38 having just completed an extension stroke bymoving in the direction of arrow 122 from a position proximate tointermediate plate 96 to a position proximate to end plate 41.

During the extension stroke, the movement of piston 38 in the directionof arrow 122 pressurizes the fluid within intake chamber 40 (shown inFIG. 6) causing inlet check valve 36 to close and piston check valve 44to open. The fluid pressurized within intake chamber 40 flows throughopen piston check valve 44 into pressure chamber 46. At the beginning ofthe extension stroke, the pressure within pressure chamber 46 is lowerthan the pressure of the fluid within accumulator coil 24. Accordingly,pump discharge check valve 48 is held closed by the pressuredifferential. Later in the extension stroke, because the volume ofintake chamber 40 is much larger than the volume of pressure chamber 46,the transfer of the fluid into pressure chamber 46 causes the pressuretherein to rise. Eventually, the pressure within pressure chamber 46exceeds the pressure of the fluid within accumulator coil 24 and pumpdischarge check valve 48 opens to allow some of the fluid withinpressure chamber 46 to flow into accumulator coil 24.

In this manner, the pump operates as a double acting pump. In preferredarrangements, the displaceable volume of intake chamber 40 is sizedlarger than the displaceable volume of pressure chamber 46 andpreferably sized approximately two times larger than the displaceablevolume of pressure chamber 46. Preferably, the quantity of fluiddischarged from the pump is about equal for each extension andretraction stroke.

During the extension stroke, the flow of the pressurized fluid throughaccumulator coil 24 and the operation of heater section 18 isessentially the same as described with respect to the retraction strokeand, as such, will not be repeated with respect to the extension stroke.

As is well known in the art, the apparatus may be operated to maintaincertain parameters such as, for example, the pressure within theaccumulator, or the pressure and temperature of the fluid delivered fromthe apparatus. One or more sensors within the delivery system orapparatus 12, may be employed to cause a controller to activate the pumpdriver housed in the drive section. The pump driver, in turn, actuatespiston shaft 80 to drive piston 38 according to the pump cycle describedabove. At times when demand is low, the controller may also cause pumppiston 38 to remain at rest.

In the preferred arrangement described above, the heater section employsa particular embodiment of a heat exchanger to transfer heat from a heatexchange fluid, e.g., engine coolant, to the pressurized fluid. Ofcourse, as would be apparent to a person skilled in the art, alternatevariations of the heater found in the embodiment discussed above may beutilized. For example, instead of an inner and outer coil for conveyingthe pressurized fluid, a single coil may be employed. Other variationson the embodiment discussed include but are not limited to alternateconfigurations that utilize a warmed channel or set of channels throughwhich the pressurized fluid is circulated, heated, and converted to agas.

More generally, however, conventional heaters may be housed in theheater section without affecting the spirit of the invention. As notedabove, the benefits of the invention are realized where a heaterfunctions within the apparatus in a space that allows for a maximizationof the volume in the accumulator. Such heaters include elements fortransferring heat to a fluid thus raising the temperature of the fluidto operational temperatures within a time frame to meet the operationalparameters of the subject system. These conventional heaters may includeelectric heaters such as heaters employing a hot wire element, fins,plates and frames, and other devices well known to those skilled in theart.

Referring to the embodiment of the apparatus shown in FIG. 1, the tankassembly including the apparatus draws in a low pressure fluid such asLNG, from tank assembly 10 and delivers the fluid in as a pressurizedgas, such as natural gas. Generally, a temperature gradient isintroduced in such a system:

-   along an axis running parallel to piston shaft 80; and,-   at right angles to piston shaft 80 varying along the length of the    shaft from a maximum in parts of heater section 18 to a nominal    gradient within the cold section and other upstream parts of    accumulator 16.

Maintaining the axial temperature gradient, that is, the temperaturegradient parallel to the axis of piston shaft 80, is important becauseany heat leak into the accumulator coil from the heater decreases thedensity of this fluid and negates the advantages realized by providingthe accumulator upstream of the heater where a cooler fluid environmentexists. The axial temperature gradient may be maintained by providingbarriers to thermal conductivity between the four sections of apparatus12. The embodiment shown provides boundary flange 63 and drive headflange 82. These flanges separate the accumulator shown as accumulator16 and heater section 18 and heater section 18 and drive section 20,respectively. As mentioned above, thermal separation between heatersection 18 and accumulator coil 24 is particularly important.

While these flanges help to thermally isolate these sections of theapparatus, the fluid flow through apparatus 12 also helps to transportheat away from cold end 14 and in the direction of warmer heater section18 and out of the system. Also, the use of accumulator coil 24 asopposed to another type of accumulator storage vessel, lengthens theconductive heat path from heater section 18 to cold end 14. Other heatpaths through the accumulator include a convective heat path through thespace surrounding accumulator coil 24. As mentioned above, insulatingmaterials can be included within this accumulator space to helpthermally isolate heater section 18 from accumulator 16 and cold end 14.Again barrier materials may also be used to reduce thermal convectionresulting from circulating gases within this accumulator space.Alternatively, the accumulator space surrounding accumulator coil 24 maybe evacuated.

A further heat path from heater section 18 into the accumulator runsalong accumulator sleeve 84. Suitable insulating materials known topersons skilled in the art may be employed to help with thermallyisolating heater section 18 from accumulator 16 and cold end 14. In theillustrated embodiment, accumulator coil 24 contains the pressurizedfluid so accumulator sleeve 84 need not be designed to containpressurized cryogenic fluids. Therefore, the selected material forsleeve 84 may be chosen with priority to thermal conductivity propertiesrather than for structural characteristics.

The transverse temperature gradient, that is, generally perpendicular topiston shaft 80, is also a potential problem when positioning apparatus12 within cryogenic tanks generally. Heat from the heater within theheater section that leaks into accumulator 16, if any, as well as heatwithin the heater section itself, causes a further temperature gradientbetween parts of apparatus 12 and cryogen space 88 within vessel 13 oftank assembly 10. Referring to FIGS. 1 and 5, support and barrier wallsor insulating walls 90 and 92 extend into vessel 13. In the embodimentshown, therefore, heater section 18 and accumulator 16 are separated andthermally insulated from tank interior 88. The support wall 90 extendedinto tank assembly 10 from outer jacket 91 where support wall 90 createstank opening 86. Defined between support wall 90 and a second or barrierwall 92 is insulated space 94, which may contain suitable insulatingmaterial and/or a vacuum space. In the embodiment shown, barrier wall 92is joined to vessel 13. The insulation space 94 in the embodiment shownin FIG. 5 is in communication with insulation space 17 surroundingvessel 13. This may be of value when utilizing a vacuum for theseinsulation spaces. However, insulation space 17 of the tank assembly mayalso be isolated from insulation space 94 with similar insulatingeffect.

As noted above, accumulator sleeve 84 is also constructed of a materialsuitable to help insulate the apparatus from cryogen space 88. In thiscase, the sleeve acts to inhibit transverse heat flow from apparatus 12through to support wall 90. Support wall 90 and accumulator sleeve 84are abutted together where each is designed to receive the other and,therefore, help support apparatus 12. In the illustrated embodiment,support wall 90 seals off apparatus 12 from cryogen space 88 nearintermediate plate 96 with a cryogen seal that encircles apparatus 12 ator near intermediate plate 96. This helps to reduce transverse and axialheat transfer. A further seal may be included around apparatus 12 nearthe entrance of tank assembly 10. In the embodiment shown such a sealmay be placed at or near drive head flange 82 such that cold end 14 isdirectly exposed to cryogen space 88.

Note, generally, that the apparatus may include an encasing chosen to,amongst other things, insulate or inhibit transverse heat flow. Whilethe embodiment includes an insulating space integrated into the cryogenvessel, this space or insulating material may be integrated into theapparatus itself to surround the heater and accumulator. This encasingmay also be used to help protect the various components of theapparatus.

The length of accumulator 16 and the length of support wall 90, whichare related in the embodiment shown, are preferably chosen such thatthis length is elongated. As accumulator 16 and support wall 90 and/orbarrier wall 92 provide a heat path into cryogenic environment 88 withintank 10, lengthening these sections helps to reduce the effect of thisheat path. In the embodiment shown, apparatus 12 is inserted into thetank interior on an angle that helps to elongate these dimensions.

Referring to FIGS. 2 and 4, in the illustrated embodiment, apparatus 12is bound together by tie rods. As described above, cold end 14 andaccumulator 16 are joined together by compression cylinder tie rods 102,and accumulator tie rods 104 run the length of accumulator 16 holdingthe accumulator between heater section 18 and cold end 14. While tierods have been found to provide a cost and maintenance advantage, thoseskilled in the art will understand that the apparatus may also be boundby numerous other means. By way of example the heater, accumulator andpump may be integrated together by threaded connections, bolts, weldedjoints, or bound by any one or combination of a variety of known meansfor attaching one device to another to make an integrated apparatus.

The materials utilized for accumulator coil 24, inner and outer tubularcoils (56, 58) in heater section 18, cylinder 42, tie rods (102, 104),intake tube 34, accumulator sleeve 84, boundary flange 63 and drive headflange 82 as well as other parts of the apparatus are chosen for,amongst other things, their capacity to react to temperature gradients,withstand high pressures and insulate against heat conduction. Suchmaterials are known to persons skilled in the art.

Referring again to FIG. 5, support wall 90 and barrier wall 92 providesupport to vessel 13 as well as apparatus 12. In the embodiment shown,support wall 90 is fixed to outer jacket 91 through opening flange 93.At the end extended into the cryogenic space, support wall 90 is thenjoined to barrier wall 92 through wall joint 117. The barrier wall 92,broken to a wider diameter approximately halfway along its length in theembodiment shown, extends back to connect to vessel 13. As such, acomplete support path is also provided from outer jacket 91 to helpsupport vessel 13 for, amongst other reasons, maintaining any desiredinsulation space such as insulation space 17.

While the embodiment discussed considers a single piston pump with twochambers, namely intake chamber 40 and pressure chamber 46, other pumparrangements may be employed to pressurize the fluid drawn from a vesselto higher pressures. For example, it is understood that a piston pumpwith more than one piston or a different number of chambers may besubstituted for the illustrated embodiment.

By way of example, the description discloses an apparatus that may beemployed to deliver a high pressure gas utilizing the properties of thegas in a denser state to enhance the effective accumulator capacity andmore easily pressurize the gas. It is understood, however, that theseproperties are realized in a general sense when the apparatus:

-   draws in a fluid at an initial temperature, T₁, and an initial    pressure, P₁;-   raises the pressure of that fluid to P₂, a pressure falling within a    pre-determined pressure range, where P₂>P₁;-   stores the fluid in an accumulator at a pressure within the    predetermined pressure range, approximately P₂;-   warms the fluid in a heater to temperature T₂, which falls within a    pre-determined temperature range that converts the fluid to a gas,    where T₂>T₁; and,-   delivers the gas at a temperature and pressure within the    pre-determined temperature and pressure ranges, approximately T₂ and    P₂.

As such, it is understood that the fluid will be drawn in as a fluid anddelivered as a gas with a higher temperature and pressure relative tothe initial temperature and pressure. In a preferred embodiment, aliquid may be drawn into the apparatus and a gas delivered from theapparatus. However, depending on the operational conditions of thestored fluid and the desired properties of the gas to be delivered, aliquid or supercritical fluid or a single phase fluid may be drawn inand a gas at or above the supercritical point may be delivered. Such agas may be thought of as a supercritical fluid or single phase fluid aswell. The invention contemplates such states for the delivered gas andstored fluid.

Therefore, as noted previously, as understood in this application,“fluids”, as understood in this application, are liquids and liquidsunder supercritical pressures. “Gases” as understood in thisapplication, are gases and gases under supercritical pressures. Theseterms are mutually exclusive. Further, while the embodiment shownincludes a hydraulic pump driver within drive section 20, numerous otherdrivers will suffice without departing significantly from the spirit ofthe invention as will be apparent to a person skilled in the art. By wayof example, these may include electric motors, mechanical or enginedrivers, pneumatic drivers, and so forth. The driver is a potential heatsource so it is preferably disposed away from the cryogen space and thecolder pump and accumulator to reduce heat transfer to the stored coldfluid. The illustrated embodiment positions the heater and/oraccumulator between the pump and the driver to assist with managing theaxial temperature gradient within apparatus 12 while allowing directfluid connections between the pump, the accumulator and the heater,thereby eliminating the need for piping between these components andreducing the number of connections which might be a source of leaksand/or failure points. The illustrated embodiment also provides aconvenient arrangement for locating piston shaft 80.

Referring to FIGS. 1 and 9, a further embodiment of tank assembly 10 isshown with the apparatus removed. This embodiment further includes alongwith support wall 90, barrier walls 92 and insulated space 94, a secondsupport wall 111 and a series of lines or pipes between the outer jacket91 and the cryogen space, namely, fluid drain pipe 106, fluid fill pipe108 and vapour vent pipe 110. These pipes may be disposed in insulationspace 94. Note that a second insulation space 112 occurs between thesecond support wall 111 and barrier wall 92.

Prior art cryogenic fuel delivery system tanks have required specialmeans for reducing heat transfer through these access pipes to tankinterior 88. However, the necessary creation of insulated space 94extending into tank 10 allows for a means of providing thesecommunication vents and pipes with an already existing extended lengthof insulated space 94. This maximizes the heat path length along thesepipes without any need to provide a system for doing so solely tosupport this plumbing.

Moreover, while not necessary, a second support wall may be included tohelp facilitate the pathway of some of the plumbing mentioned (106, 108,110) and/or to provide additional support to the support wall 90 and,consequently, to the apparatus when engage in housing space 21. Theembodiment of the tank shown in FIG. 9 includes second support wall 111that provides additional support for vessel 13 as well as the apparatus.Again, the space between barrier wall 92 and support wall 90 providesfor two insulation spaces (94, 112) divided by second support wall 111.Here second support wall 111 is fastened to the outer jacket. The lengthof second support wall 111 is approximately one-half of the length ofsupport wall running from the outer jacket to intermediate flange 115.This provides two insulation channels for plumbing wherein fluid fillpipe 108 runs generally through space 94 and fluid drain pipe 106 andvapour vent pipe 110 run through space 112.

Fluid drain pipe 106, 108 and vapour vent pipe 110 also provide for afurther support means for support wall 90 and vessel 13 as each may besecured to the outer jacket 91 and either intermediate flange 115, asshown, or wall joint 117 which connect support wall 90 and barrier wall92. As both intermediate flange 115 and wall joint 117 are connected tovessel 13 through barrier wall 92, further support is leant to the tankassembly as a whole via these pipe configurations.

Referring to a further embodiment of the tank assembly shown in FIG. 10,an accumulator and pump are integrated into tank assembly 130 whereapparatus 12 is disposed in thermal insulation space 133 between vessel132 and outer jacket 134 where the outer jacket is expanded away fromvessel 132 to provide for insulation space 133. Support wall 135 isshown in the embodiment and may be incorporated to help structurallycontain and/or thermally isolate apparatus 12. An alternate embodimentneed not include wall 135 wherein insulation space 133 is part ofinsulation space 131. Further, insulation space 133 may be isolated bysupport wall 135 from insulation space 131. Alternately, insulationspace 133 may be in communication with insulation space 131 throughsupport wall 135 such that an evacuated space used in insulation spaces131 and 133 is shared. Here intake tube 136 is extended from apparatus12 into the cryogen space 138. Again, the heater section, accumulatorand pump are incorporated into the tank assembly within the insulatingspace bounded by jacket flange 140. In principle, a pressurized gaseousfuel is delivered from the tank assembly by the same process describeabove in regards to the interaction of the apparatus and stored fluidwithin the tank assembly as a whole. As such, for the purposes ofbrevity, it will not be discussed again. The main difference is theplacement of apparatus 12 within tank assembly 130. The accumulatorstill forms part of the assembly, storing a pressurized fluid thusderiving the advantages set out above.

By way of example but in no way limiting the scope of the disclosedinvention, the following includes some approximate system detailsregarding the design parameters of an embodiment that would beappropriate for delivering high pressure natural gas to an engine from acryogenic environment:

Fuel storage temperature: <200 K Accumulator operational pressure:5000-5600 psig Operational heat bath temperature: 283-343 K Inner andouter coil volume: 1.65 × 10⁵ mm³ Inner and outer coil internaldiameter: 3.86 mm Accumulator coil volume: 3.32 × 10⁵ mm³ Accumulatorcoil internal diameter: 6.22 mm Pressure chamber vol. (extended): 3.74 ×10⁵ mm³ Pressure chamber vol. (retracted): 3.44 × 10⁵ mm³

As will be apparent to those skilled in the art in the light of theforegoing disclosure, many alterations and modifications are possible inthe practice of this invention without departing from the spirit orscope thereof. Accordingly, the scope of the invention is to beconstrued in accordance with the substance defined by the followingclaims.

1. A cryogenic tank assembly comprising: a. a vessel defining a cryogenspace capable of storing a fluid at a cryogenic temperature and aninitial pressure; b. a pump comprising: i. an intake opening disposed insaid cryogen space for receiving a quantity of said fluid from saidcryogen space; ii. a pressurizing device capable of pressurizing saidquantity of said fluid to a pre-determined pressure, said pre-determinedpressure being greater than said initial pressure and said pressurizingdevice being in communication with said intake opening; and, iii. a highpressure discharge passage in communication with said pressurizingdevice for discharging said quantity of said fluid from saidpressurizing device, c. an accumulator comprising: i. an entrance forreceiving said quantity of said fluid from said high pressure dischargepassage; ii. a storage volume in communication with said entrance; and,iii. an exit in communication with said storage volume for deliveringsaid quantity of said fluid, wherein a percentage of said accumulator isdisposed within said cryogen space.
 2. A cryogenic tank assembly asclaimed in claim 1 further comprising a housing, said housingsurrounding said percentage of said accumulator, said housing providingstructural support to said accumulator.
 3. A cryogenic tank assembly asclaimed in claim 1 further comprising a heater capable of receiving saidquantity of said fluid through said exit, said heater comprising: a. aheater inlet; and, b. a delivery outlet capable of delivering saidquantity of said fluid as a gas at a pre-determined temperature, saidpre-determined temperature being greater than said cryogenictemperature.
 4. A cryogenic tank assembly as claimed in claim 3 whereina percentage of said heater is disposed within said cryogen space.
 5. Acryogenic tank assembly as claimed in claim 3 further comprising ahousing, said housing surrounding said percentage of said accumulator,said housing providing thermal insulation between said accumulator andsaid cryogenic space.
 6. A cryogenic tank assembly as claimed in claim5, wherein said housing comprises an inner wall defining a housing spaceand an outer wall surrounding said inner wall, said outer wall defininga thermal insulation space between said inner wall and said outer wall,and said outer wall comprising an outer surface, a percentage of saidouter surface facing said cryogen space, wherein said percentage of saidaccumulator is within said housing space.
 7. A cryogenic tank assemblyas claimed in claim 3, further comprising a housing defining a housingspace, said housing comprising a first end and a second end, said firstend attached to said vessel and said second end extending into saidcryogen space such that a percentage of said housing space is definedwithin said cryogen space, wherein a second percentage of saidaccumulator is disposed within said housing space.
 8. A cryogenic tankassembly as claimed in claim 4 further comprising a housing, saidhousing surrounding: a. said percentage of said accumulator disposedwithin said cryogen space; and, b. said percentage of said heaterdisposed within said cryogen space, said housing providing thermalinsulation between: said percentage of said accumulator and said cryogenspace; and, said percentage of said heater and said cryogen space.
 9. Acryogenic tank assembly as claimed in claim 8, wherein said housingcomprises an inner wall defining a housing space and an outer wallsurrounding said inner wall, whereby said outer wall defines a thermalinsulation space between said inner wall and said outer wall, and saidouter wall comprises an outer surface, and at least a portion of saidouter surface faces said cryogen space, wherein: a. said percentage ofsaid accumulator disposed within said cryogen space; and, b. saidpercentage of said heater disposed within said cryogen space aredisposed within said housing space.
 10. A cryogenic tank assembly asclaimed in claim 5, further comprising a housing defining a housingspace, said housing comprising a first end and a second end, said firstend attached to said vessel and said second end extending into saidcryogen space such that a percentage of said housing space is definedwithin said cryogen space, wherein: a second percentage of saidaccumulator is disposed within said housing space; and, a secondpercentage of said heater is disposed within said housing space.
 11. Acryogenic tank assembly as claimed in claim 10, wherein said secondpercentage of said accumulator is wholly disposed within said cryogenspace.
 12. A cryogenic tank assembly as claimed in claim 11, whereinsaid second percentage of said heater is wholly disposed within saidcryogen space.
 13. A cryogenic tank assembly as claimed in claim 5,further comprising a suitable thermal insulator, said insulatorproviding insulation between said heater and said cryogen space.
 14. Acryogenic tank assembly as claimed in claim 5 wherein said heatercomprises a heating substance and at least one channel for housing saidheating substance wherein said heating substance is capable of warmingsaid cryogenic fluid such that said cryogenic fluid is converted to saidgas.
 15. A cryogenic tank assembly as claimed in claim 14 wherein saidheating substance is a heating fluid capable of being circulated throughsaid at least one channel.
 16. A cryogenic tank assembly as claimed inclaim 15 wherein said gas is capable of being delivered through saiddelivery outlet for use as a fuel in an engine and said heating fluid isengine coolant.
 17. A cryogenic tank assembly as claimed in claim 14wherein said heater further comprises a fluid passageway for directingsaid fluid from said heater inlet through said at least one channel tosaid delivery outlet.
 18. A cryogenic tank assembly as claimed in claim17 wherein said heater further comprises a pipe defining said fluidpassageway, wherein said pipe is disposed in said channel.
 19. Acryogenic tank assembly as claimed in claim 1, further comprising anouter jacket surrounding said vessel, said outer jacket defining anvessel insulation volume disposed between said outer jacket and saidvessel.
 20. A cryogenic tank assembly as claimed in claim 19 whereinsaid vessel insulation volume comprises an evacuated space.
 21. Acryogenic tank assembly as claimed in claim 9, further comprising anouter jacket surrounding said vessel, said outer jacket defining avessel insulation volume disposed between said outer jacket and saidvessel wherein said thermal insulation space is in communication withsaid vessel insulation volume.
 22. A cryogenic tank assembly as claimedin claim 21 wherein said inner wall comprises: a jacket end that isattached to said outer jacket; and, a cryogen end that extends into saidcryogen space, and said outer wall comprises: a vessel end that isattached to said vessel; and, a second cryogen end that extends intosaid cryogen space and attaches to said cryogen end, such that saidinner wall and said outer wall provide support to said vessel withinsaid outer jacket.
 23. A cryogenic tank assembly as claimed in claim 22,further comprising at least one access passage disposed in said thermalinsulation space for communicating between said cryogen space andoutside of said cryogen tank assembly.
 24. A cryogenic tank assembly asclaimed in claim 1 wherein said pump is a reciprocating pump furthercomprising at least one piston disposed within a cylinder, said pistondividing said cylinder into an intake chamber and a pressure chamber.25. A cryogenic tank assembly as claimed in claim 24 wherein said intakechamber is in communication with said intake opening through an intakevalve, said intake valve permits one-way flow of said quantity of saidfluid into said intake chamber through said intake valve.
 26. Acryogenic tank assembly as claimed in claim 24 wherein said intakechamber is in communication with said pressure chamber through a pistonvalve capable of allowing one-way flow of said quantity of said fluidinto said pressure chamber from said intake chamber.
 27. A cryogenictank assembly as claimed in claim 26 wherein said piston valve isdisposed in said piston.
 28. A cryogenic tank assembly as claimed inclaim 24 wherein said pressure chamber is in communication with saidhigh pressure discharge passage such that said quantity of said fluid isflowable into said high pressure discharge passage once said fluid is atsaid pre-determined pressure.
 29. A cryogenic tank assembly as claimedin claim 28 wherein a high pressure valve prevents the flow of saidquantity of said fluid from said pressure chamber into said highpressure discharge passage until the pressure of said quantity of saidfluid is at or above said pre-determined pressure.
 30. A cryogenic tankassembly as claimed in claim 24 further comprising: a drive unit; and, apiston rod wherein said drive unit is a hydraulic drive comprising ahydraulic piston disposed within a hydraulic cylinder wherein ahydraulic fluid is deliverable to said drive unit causing areciprocating motion of said hydraulic piston, wherein saidreciprocating motion is transferable to said at least one piston throughsaid piston rod.
 31. A cryogenic tank assembly as claimed in claim 3,wherein said accumulator is mounted between said heater and said pump.32. A cryogenic tank assembly as claimed in claim 31 wherein said highpressure discharge passage is joined directly to said entrance.
 33. Acryogenic tank assembly as claimed in claim 31 wherein said exit isjoined directly to said heater inlet.
 34. A cryogenic tank assembly asclaimed in claim 31, further comprising a casing assembly, said casingassembly integrating said heater, said accumulator and said pump.
 35. Acryogenic tank assembly as claimed in claim 34, wherein said casingassembly comprises at least one tie rod.
 36. A cryogenic tank assemblycomprising: a. an outer jacket; b. a vessel generally surrounded by saidouter jacket, said vessel defining a cryogen space, said cryogen spacecapable of storing a fluid at a cryogenic temperature and an initialpressure; c. a housing, said housing comprising a wall defining ahousing space, said wall comprising a first end and a second end, saidfirst end attached to said outer jacket and said second end extendinginto said cryogen space such that said housing space extends into saidcryogen space, d. a pump comprising: i. an intake opening disposed insaid cryogen space capable of receiving a quantity of said fluid fromsaid cryogen space; ii. a pressurizing means capable of pressurizingsaid quantity of said fluid to a pre-determined pressure, saidpre-determined pressure being greater than said initial pressure andsaid pressurizing means being in communication with said intake opening;and, iii. a high pressure discharge passage in communication with saidpressurizing means for discharging said quantity of said fluid from saidpressurizing means, e. an accumulator comprising: i. an entrance forreceiving said quantity of said fluid from said high pressure dischargepassage; ii. a storage volume in communication with said entrance; and,iii. an exit in communication with said storage volume for deliveringsaid quantity of said fluid, wherein said accumulator is disposed withinsaid cryogen space.
 37. A cryogenic tank assembly as claimed in claim 36further comprising a heater, said heater comprising: a. a heater inletcapable of receiving said quantity of said fluid from said exit; and, b.a delivery outlet capable of delivering said quantity of said fluid at apre-determined temperature, said pre-determined temperature beinggreater than said cryogenic temperature.
 38. A cryogenic tank assemblyas claimed in claim 37 wherein said housing further comprises an outerwall generally surrounding said wall, whereby a thermal insulation spaceis defined between said wall and said outer wall such that said housingprovides thermal insulation between said accumulator and said cryogenspace.
 39. A cryogenic tank assembly as claimed in claim 38 wherein saidinsulation space comprises an evacuated space.
 40. A cryogenic tankassembly as claimed in claim 38 wherein said heater is also housed insaid cryogen space and said thermal insulation space is capable ofproviding thermal insulation between said heater and said cryogen space.41. A cryogenic tank assembly comprising: a. a vessel defining a cryogenspace capable of storing a fluid at a cryogenic temperature and aninitial pressure; b. an outer jacket surrounding said vessel defining:i. an assembly space; and, ii. an insulation space between said vesseland said outer jacket wherein said assembly space comprises said cryogenspace and said insulation space; c. a pump comprising: i. an intakeopening disposed in said cryogen space for receiving a quantity of saidfluid from said cryogen space; ii. a pressurizing device capable ofreceiving said quantity of said fluid from said intake opening andpressurizing said quantity of said fluid to a pre-determined pressure,said pre-determined pressure being greater than said initial pressure;and, iii. a high pressure discharge passage in communication with saidpressurizing device for discharging said quantity of said fluid fromsaid pressurizing device, d. an accumulator comprising: i. an entrancefor receiving said quantity of said fluid from said high pressuredischarge passage; ii. a storage volume in communication with saidentrance; and, iii. an exit in communication with said storage volumefor delivering said quantity of said fluid, wherein a percentage of saidaccumulator is disposed within said assembly space.
 42. A cryogenic tankassembly as claimed in claim 41 wherein said percentage of saidaccumulator is disposed within said insulation space.
 43. A cryogenictank assembly as claimed in claim 41, further comprising a heatercapable of receiving said quantity of said fluid through said exit, saidheater comprising: a. a heater inlet; and, b. a delivery outlet capableof delivering said quantity of said fluid as a gas at a pre-determinedtemperature, said pre-determined temperature being greater than saidcryogenic temperature.
 44. A cryogenic tank assembly as claimed in claim43 wherein a percentage of said heater is disposed within said assemblyspace.
 45. A cryogenic tank assembly as claimed in claim 43 wherein saidheater comprises a heating substance and at least one channel forhousing said heating substance wherein said heating substance is capableof warming said cryogenic fluid such that said cryogenic fluid isconverted to said gas.
 46. A cryogenic tank assembly comprising: a. avessel defining a cryogen space capable of storing a fluid at acryogenic temperature and an initial pressure; b. an outer jacketsurrounding said vessel defining: i. an assembly space; and, ii. aninsulation space between said vessel and said outer jacket; wherein saidassembly space comprises said insulation space and said cryogen space,c. a support wall comprising a first end and a second end, said firstend attached to said outer jacket and said second end extending intosaid cryogen space, wherein said support wall defines a housing spacewithin said cryogen space, d. a barrier wall comprising a vessel end anda cryogen end, said vessel end attached to said vessel and said cryogenend extended into said cryogen space and attached to said second end,wherein said barrier wall defines a second insulation space between saidsupport wall and said barrier wall, e. a pump comprising: i. acompression cylinder comprising an intake end and a discharge end; ii.an end flange abutted against said intake end; iii. an intermediateflange abutted against said discharge end; iv. a reciprocating pistonmovably disposed within said compression cylinder, said reciprocatingpiston comprising an intake face and a discharge face; v. an intakechamber defined within said cylinder between said intake face and saidend flange; vi. a pressure chamber defined within said cylinder betweensaid discharge face and said intermediate flange; vii. an intake openingdisposed within said cryogen space for receiving a quantity of saidfluid from said cryogen space; viii. a intake check valve capable ofallowing one-way flow of said fluid into said intake chamber from saidintake opening wherein said intake check valve is disposed within saidend flange; ix. a piston check valve disposed within said piston capableof allowing one-way flow of said fluid from said intake chamber intosaid pressure chamber; x. an accumulator check valve disposed withinsaid intermediate flange capable of allowing one-way flow of said fluidfrom said pressure chamber into a high pressure discharge passage, f. anaccumulator fixed in said housing space said accumulator comprising: i.an entrance in communication with said high pressure discharge passage;ii. a coiled tube defining a storage volume, said storage volume incommunication with said entrance; and, iii. an exit in communicationwith said storage volume for delivering said quantity of said fluid,wherein a percentage of said accumulator is disposed within saidassembly space.
 47. A method of storing a pressurized fluid comprisingsequentially: a. receiving a quantity of a fluid from a cryogen space atan initial pressure, said cryogen space defined by a vessel; b.pressurizing said quantity of said fluid to within a pre-determinedpressure range wherein said initial pressure is less than saidpredetermined pressure range; and, c. storing said quantity of saidfluid within an accumulator disposed within said cryogen space whereinsaid quantity of said fluid is readily available for delivery withinsaid pre-determined pressure range and wherein there is no fluidcommunication from the accumulator to the cryogenic space.
 48. A methodof storing and delivering a gas comprising sequentially: a. receiving aquantity of a fluid from a cryogen space at an initial pressure and aninitial cryogenic temperature, said cryogen space defined by a vessel;b. pressurizing said quantity of said fluid to within a pre-determinedpressure range wherein said initial pressure less than saidpredetermined pressure range; c. storing a percentage of said quantityof said fluid within an accumulator disposed within said cryogen space;d. heating said quantity of said fluid and transforming it to said gaswithin a pre-determined temperature range; and, e. delivering said gaswithin said pre-determined pressure range and within said pre-determinedtemperature range wherein said initial cryogenic temperature is lessthan said pre-determined temperature range and wherein there is no fluidcommunication from the accumulator to the cryogenic space.
 49. A methodof storing and delivering a pressurized gas as claimed in claim 48wherein said pre-determined pressure range comprises pressures above thesupercritical point of said fluid when said fluid is at said initialcryogenic temperature.
 50. A method of storing and delivering a gascomprising sequentially: a. receiving a quantity of a fluid from acryogen space at an initial pressure and an initial cryogenictemperature, said cryogen space defined by a vessel, said vesselsurrounded by an outer jacket that defines a tank assembly space, saidtank assembly space comprising said cryogen space; b. pressurizing saidquantity of said fluid to within a pre-determined pressure range whereinsaid initial pressure less than said predetermined pressure range; c.storing a percentage of said quantity of said fluid within anaccumulator disposed within said tank assembly space; d. heating saidquantity of said fluid and transforming it to said gas within apre-determined temperature range; and, e. delivering said gas withinsaid pre-determined pressure range and within said pre-determinedtemperature range wherein said initial cryogenic temperature is lessthan said pre-determined temperature range and wherein there is no fluidcommunication from the accumulator to the cryogenic space.
 51. Anapparatus as claimed in claim 1 wherein said fluid comprises at leastone of methane, methanol, ethane, propane, hydrogen, oxygen or butane.52. An apparatus as claimed in any one of claim 1 wherein said fluidcomprises an element that is combustible as a gas.
 53. A cryogenic tankassembly comprising: a. a vessel defining a cryogen space capable ofstoring a fluid at a cryogenic temperature and an initial pressure; b. apump comprising: i. an intake opening disposed in said cryogen space forreceiving a quantity of said fluid from said cryogen space; ii. apressurizing device capable of pressurizing said quantity of said fluidto a pre-determined pressure, said pre-determined pressure being greaterthan said initial pressure and said pressurizing device being incommunication with said intake opening; and, iii. a high pressuredischarge passage in communication with said pressurizing device fordischarging said quantity of said fluid from said pressurizing device,c. a conduit comprising: i. an entrance for receiving said quantity ofsaid fluid from said high pressure discharge passage; ii. a storagevolume in communication with said entrance; and, iii. an exit incommunication with said storage volume for delivering said quantity ofsaid fluid, d. a heater capable of receiving said quantity of said fluidthrough said exit, said heater comprising: i. a heater inlet; and, ii. adelivery outlet capable of delivering said quantity of said fluid as agas at a pre-determined temperature, said predetermined temperaturebeing greater than said cryogenic temperature, wherein a percentage ofsaid heater is disposed within said cryogen space.
 54. A cryogenic tankassembly as claimed in claim 53 further comprising a housing, saidhousing surrounding said percentage of said heater, said housingproviding structural support to said heater.
 55. A cryogenic tankassembly as claimed in claim 53, further comprising a housing defining ahousing space, said housing comprising a first end and a second end,said first end attached to said vessel and said second end extendinginto said cryogen space such that a percentage of said housing space isdefined within said cryogen space, wherein a second percentage of saidheater is disposed within said housing space.
 56. A cryogenic tankassembly as claimed in claim 55 wherein said second percentage of saidheater is wholly within said cryogen space.
 57. A cryogenic tankassembly as claimed in claim 53 wherein said exit is a distance fromsaid entrance, said distance providing thermally insulation between saidcryogen space and said exit.
 58. A cryogenic tank assembly as claimed inclaim 53 further comprising a housing, said housing surrounding saidpercentage of said heater disposed within said cryogen space, saidhousing providing thermal insulation between said percentage of saidheater and said cryogen space.
 59. A cryogenic tank assembly as claimedin claim 58 wherein said housing provides thermal insulation betweensaid conduit and said cryogen space.
 60. A cryogenic tank assembly asclaimed in claim 58, wherein said housing comprises an inner walldefining a housing space and an outer wall surrounding said inner wall,whereby said outer wall defines a thermal insulation space between saidinner wall and said outer wall, and said outer wall comprises an outersurface, and at least a portion of said outer surface faces said cryogenspace, wherein: a. said conduit; and, b. said percentage of said heaterdisposed within said cryogen space are disposed within said housingspace.
 61. A cryogenic tank assembly as claimed in claim 53 wherein saidheater comprises a heating substance and at least one channel forhousing said heating substance wherein said heating substance is capableof warming said cryogenic fluid.
 62. A cryogenic tank assembly asclaimed in claim 61 wherein said heating substance is a heating fluidcapable of being circulated through said at least one channel.
 63. Acryogenic tank assembly as claimed in claim 62 wherein said gas iscapable of being delivered through said delivery outlet for use as afuel in an engine and said heating fluid is engine coolant.
 64. Acryogenic tank assembly as claimed in claim 53 further comprising adrive unit capable of driving said pump wherein said drive unit isdisposed outside of said cryogen space.
 65. A cryogenic tank assembly asclaimed in claim 64 further comprising a piston rod wherein said driveunit is in communication with said pump through said piston rod.
 66. Acryogenic tank assembly as claimed in claim 53 wherein said conduitfurther comprises: a. a sleeve, said sleeve defining an passage spacewithin said conduit; and, b. a storage vessel defining said storagevolume wherein said storage volume is disposed in said passage space.67. A cryogenic tank assembly as claimed in claim 66 wherein saidstorage vessel comprises at least one coiled tube.
 68. A cryogenic tankassembly as claimed in claim 66 wherein said sleeve is a thermalinsulator.
 69. A cryogenic tank assembly comprising: a. an outer jacket;b. a vessel generally surrounded by said outer jacket, said vesseldefining a cryogen space, said cryogen space capable of storing a fluidat a cryogenic temperature and an initial pressure; c. a housing, saidhousing comprising a wall defining a housing space, said wall comprisinga first end and a second end, said first end attached to said outerjacket and said second end extending into said cryogen space such thatsaid housing space extends into said cryogen space, d. a pumpcomprising: i. an intake opening disposed in said cryogen space capableof receiving a quantity of said fluid from said cryogen space; ii. apressurizing means capable of pressurizing said quantity of said fluidto a pre-determined pressure, said pre-determined pressure being greaterthan said initial pressure and said pressurizing means being incommunication with said intake opening; and, iii. a high pressuredischarge passage in communication with said pressurizing means fordischarging said quantity of said fluid from said pressurizing means, e.a conduit comprising: i. an entrance for receiving said quantity of saidfluid from said high pressure discharge passage; ii. a storage volume incommunication with said entrance; and, iii. an exit in communicationwith said storage volume for delivering said quantity of said fluid, f.a heater disposed within said cryogen space, said heater comprising: i.a heater inlet capable of receiving said quantity of said fluid fromsaid exit; and, ii. a delivery outlet capable of delivering saidquantity of said fluid at a pre-determined temperature, saidpre-determined temperature being greater than said cryogenic temperaturesaid conduit providing thermal insulation between said heater and saidcryogen space.
 70. A cryogenic tank assembly as claimed in claim 69wherein said housing further comprises an outer wall generallysurrounding said wall, whereby a thermal insulation space is definedbetween said wall and said outer wall such that said housing providesthermal insulation between said heater and said cryogen space.
 71. Acryogenic tank assembly as claimed in claim 70 wherein said insulationspace comprises an evacuated space.
 72. A cryogenic tank assembly asclaimed in claim 70 wherein said thermal insulation space has aconductivity of less than 15 W/m times·K.
 73. A cryogenic tank assemblyas claimed in claim 69, wherein said conduit further comprises anevacuated space surrounding said storage volume.
 74. A cryogenic tankassembly comprising: a. a vessel defining a cryogen space capable ofstoring a fluid at a cryogenic temperature and an initial pressure; b.an outer jacket surrounding said vessel defining: i. an assembly space;and, ii. an insulation space between said vessel and said outer jacket;wherein said assembly space comprises said insulation space and saidcryogen space, c. a support wall comprising a first end and a secondend, said first end attached to said outer jacket and said second endextending into said cryogen space, wherein said support wall defines ahousing space within said cryogen space, d. a barrier wall comprising avessel end and a cryogen end, said vessel end attached to said vesseland said cryogen end extended into said cryogen space and attached tosaid second end, wherein said barrier wall defines a second insulationspace between said support wall and said barrier wall, e. a pumpcomprising: i. a compression cylinder comprising an intake end and adischarge end; ii. an end flange abutted against said intake end; iii.an intermediate flange abutted against said discharge end; iv. areciprocating piston movably disposed within said compression cylinder,said reciprocating piston comprising an intake face and a dischargeface; v. an intake chamber defined within said cylinder between saidintake face and said end flange; vi. a pressure chamber defined withinsaid cylinder between said discharge face and said intermediate flange;vii. an intake opening disposed within said cryogen space for receivinga quantity of said fluid from said cryogen space; viii. a intake checkvalve capable of allowing one-way flow of said fluid into said intakechamber from said intake opening wherein said intake check valve isdisposed within said end flange; ix. a piston check valve disposedwithin said piston capable of allowing one-way flow of said fluid fromsaid intake chamber into said pressure chamber; x. an conduit checkvalve disposed within said intermediate flange capable of allowingone-way flow of said fluid from said pressure chamber into a highpressure discharge passage, f. an conduit fixed in said housing spacesaid conduit comprising: i. an entrance in communication with said highpressure discharge passage; ii. a coiled tube defining a storage volume,said storage volume in communication with said entrance; and, iii. anexit in communication with said storage volume for delivering saidquantity of said fluid, g. a heater, a percentage of said heater isdisposed within said assembly space, said heater comprising i. a coiledpipe disposed within at least one heat bath channel, wherein said fluidis receivable into said coiled pipe from said exit, and ii. a heatingfluid is capable of being circulated through said at least one heat bathchannel such that said fluid is deliverable from said pipe at atemperature higher than said cryogenic temperature.
 75. A method ofstoring and delivering a gas comprising sequentially: a. receiving aquantity of a fluid from a cryogen space at an initial pressure and aninitial cryogenic temperature, said cryogen space defined by a vessel;b. pressurizing said quantity of said fluid to within a pre-determinedpressure range wherein said initial pressure less than saidpre-determined pressure range; c. delivering said quantity of said fluidto a heater thermally insulated from said cryogen space; d. heating saidquantity of said fluid with said heater within said cryogen space andtransforming it to said gas within a pre-determined temperature range;and, e. delivering said gas within said pre-determined pressure rangeand within said pre-determined temperature range wherein said initialcryogenic temperature is less than said pre-determined temperaturerange.
 76. A method of storing and delivering a pressurized gas asclaimed in claim 75 wherein said pre-determined pressure range comprisespressures above the supercritical point of said fluid when said fluid isat said initial cryogenic temperature.
 77. A method of storing anddelivering a gas comprising sequentially: a. receiving a quantity of afluid from a cryogen space at an initial pressure and an initialcryogenic temperature, said cryogen space defined by a vessel, saidvessel surrounded by an outer jacket that defines a tank assembly space,said tank assembly space comprising said cryogen space; b. pressurizingsaid quantity of said fluid to within a pre-determined pressure rangewherein said initial pressure less than said pre-determined pressurerange; c. delivering said quantity of said fluid to a heater disposedwithin said tank assembly space; d. heating said quantity of said fluidwith said heater and transforming it to said gas within a pre-determinedtemperature range; and, e. delivering said gas within saidpre-determined pressure range and within said pre-determined temperaturerange wherein said initial cryogenic temperature is less than saidpre-determined temperature range.